Nickel(II)-Induced Excimer Formation of a Naphthalene-Based Fluorescent Probe for Living Cell Imaging

TLDR: Ni(2+)-induced intramolecular excimer formation of a naphthalene-based novel fluorescent probe, 1-[ (naphthalen-3-yl)methylthio]-2-[(naphthaen-6-yl] methylthio]ethane (L), has been investigated for the first time and nicely demonstrated by excitation spectra, a fluorescence lifetime experiment, and (1)H NMR titration.

Abstract: Ni2+-induced intramolecular excimer formation of a naphthalene-based novel fluorescent probe, 1-[(naphthalen-3-yl)methylthio]-2-[(naphthalen-6-yl)methylthio]ethane (L), has been investigated for the first time and nicely demonstrated by excitation spectra, a fluorescence lifetime experiment, and 1H NMR titration. The addition of Ni2+ to a solution of L (DMSO:water = 1:1, v/v; λem = 345 nm, λex = 280 nm) quenched its monomer emission, with subsequent enhancement of the excimer intensity (at 430 nm) with an isoemissive point at 381 nm. The fluorescence lifetime of free L (0.3912 ns) is much lower than that of the nickel(2+) complex (1.1329 ns). L could detect Ni2+ as low as 1 × 10–6 M with a fairly strong binding constant, 2.0 × 104 M–1. Ni2+-contaminated living cells of plant origin could be imaged using a fluorescence microscope.